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adjustment altitude arithmetical mean axis azimuth bearing and distance bisect bubble celestial sphere centre chains circle clamp co-ordinates collimation computed contour correction cosec cross-wires declination deduced deflection departure difference east Elevation elongation equal equator error feet field-book fixed given graduated Greenwich Greenwich mean height Hence Horizontal Distances hour-angle inches instrument intersection latitude length levelling screws line of collimation line of sight longitude magnetic mark measured meridian altitude method micrometer minus noon observer's obtained parallax plotted plumb-bob Point of Aries polar distance pole prime vertical radius reading reduced referring-mark refraction right angles right ascension scale shaft side sidereal interval sine square stadia staff staff-reading stake star star's station subtract surface survey Table tangent screw telescope theodolite transition curve traverse triangle trig true bearing true meridian unclamp underground vernier plate vertical angle wires zenith distance
Page 47 - All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.
Page 167 - The sides of a triangle are proportional to the sines of the opposite angles.
Page 362 - If a ray of light suffers two successive reflections in the same plane by two plane mirrors, the angle between the first and last direction of the ray is twice the angle of the mirrors. D is set parallel to CX, and mirror C turns with arm B. The angle between SC and S...
Page 107 - The area of a triangle is equal to half the product of any two of its sides multiplied by the sine of the included angle, radius being unity.
Page 230 - ... at greater distances than those of Duddell's experiments, which only extended to sixty miles, we find from simple mathematical, or rather geographical, considerations that the radius of the circle in which the...
Page ii - Genetically Considered— Ores and Minerals Considered Economically.— Mine Sampling and Ore Valuation.— The Examination and Valuation of Mines.- INDEX. " A work which should find a place in the library of every mining engineer.
Page 204 - The difference between the two readings on the arc brought to seconds, divided by the difference of the two readings of the object end of the bubble, gives the value of one division of the level in seconds of arc. Thus :— Elevation. 01-jcct end of bubble. 1st observation . . . 7° 3 28" 18 divisions 2nd ,,...700 6 Difference . . . o 3 28 12 Value of one division = = 17
Page 72 - Therefore, the sum of the northings should equal the sum of the southings.